To have sexual intercourse with a girl. Can be shortened to chuck it in her.

Megan: "How are you and Hillary doing?"
Chad: "Last night I told her I wanted to beat it up, but then she freaked out and bounced for some reason. She probably was just afraid that I might knock her up if I chucked my junk in her. She was bitching and shit but I didn't really hear what she said because I wasn't listening."
Megan: "Wow, you're such a sensitive guy. I can't imagine why she left you."